Ferroelectric capacitors have various uses in RF systems including as voltage-tunable devices. Some benefits of ferroelectric capacitors are small size, integration of different values and functions of capacitance, and low cost. Applications for ferroelectric capacitors may include tunable filters, voltage controlled oscillators, tunable phase shifters, tunable matching networks, low-impedance power supplies, decoupling high-frequency signals at an IC bonding pad, or others. Integrated circuits including ferroelectric capacitors may, for example, be used in portable electronics for low-power wireless communication (e.g., cellular phones, pagers, PDAs, and so forth), directional antenna systems, high clock-rate microphones, miniature DC to DC converters, or other devices.
The fabrication of tunable ferroelectric capacitors can sometimes lead to undesired conditions. For example as shown in FIG. 1, a hillock that forms on a bottom electrode can cause defects and deformations resulting in a reduction in breakdown voltage of the dielectric film. As another example shown in FIG. 2, vertical dendrite growth can cause capacitor failure in the field during use.